linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Wei Wang <wei.w.wang@intel.com>,
	virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org,
	akpm@linux-foundation.org, dgilbert@redhat.com
Cc: torvalds@linux-foundation.org, pbonzini@redhat.com,
	liliang.opensource@gmail.com, yang.zhang.wz@gmail.com,
	quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com,
	peterx@redhat.com, quintela@redhat.com,
	Halil Pasic <pasic@linux.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting
Date: Thu, 27 Dec 2018 12:59:04 +0100	[thread overview]
Message-ID: <de167161-b586-6aee-d6a5-a90d47bbe1d4@de.ibm.com> (raw)
In-Reply-To: <0661b05a-d9d0-d374-44e8-2583463e94c2@de.ibm.com>

On 27.12.2018 12:31, Christian Borntraeger wrote:
> This patch triggers random crashes in the guest kernel on s390 early during boot.
> No migration and no setting of the balloon is involved.
> 

Adding Conny and Halil,

As the QEMU provides no PAGE_HINT feature yet, this quick hack makes the
guest boot fine again:


diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 728ecd1eea305..aa2e1864c5736 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -492,7 +492,7 @@ static int init_vqs(struct virtio_balloon *vb)
                callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
        }
 
-       err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
+       err = vb->vdev->config->find_vqs(vb->vdev, 3, //VIRTIO_BALLOON_VQ_MAX,
                                         vqs, callbacks, names, NULL, NULL);
        if (err)
                return err;


To me it looks like that virtio_ccw_find_vqs will abort if any of the virtqueues 
that it is been asked for does not exist (including the earlier ones).


Christian

> 
> On 27.08.2018 03:32, Wei Wang wrote:
>> The new feature, VIRTIO_BALLOON_F_FREE_PAGE_HINT, implemented by this
>> series enables the virtio-balloon driver to report hints of guest free
>> pages to host. It can be used to accelerate virtual machine (VM) live
>> migration. Here is an introduction of this usage:
>>
>> Live migration needs to transfer the VM's memory from the source machine
>> to the destination round by round. For the 1st round, all the VM's memory
>> is transferred. From the 2nd round, only the pieces of memory that were
>> written by the guest (after the 1st round) are transferred. One method
>> that is popularly used by the hypervisor to track which part of memory is
>> written is to have the hypervisor write-protect all the guest memory.
>>
>> This feature enables the optimization by skipping the transfer of guest
>> free pages during VM live migration. It is not concerned that the memory
>> pages are used after they are given to the hypervisor as a hint of the
>> free pages, because they will be tracked by the hypervisor and transferred
>> in the subsequent round if they are used and written.
>>
>> * Tests
>> 1 Test Environment
>>     Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz
>>     Migration setup: migrate_set_speed 100G, migrate_set_downtime 400ms
>>
>> 2 Test Results (results are averaged over several repeated runs)
>>     2.1 Guest setup: 8G RAM, 4 vCPU
>>         2.1.1 Idle guest live migration time
>>             Optimization v.s. Legacy = 620ms vs 2970ms
>>             --> ~79% reduction
>>         2.1.2 Guest live migration with Linux compilation workload
>>           (i.e. make bzImage -j4) running
>>           1) Live Migration Time:
>>              Optimization v.s. Legacy = 2273ms v.s. 4502ms
>>              --> ~50% reduction
>>           2) Linux Compilation Time:
>>              Optimization v.s. Legacy = 8min42s v.s. 8min43s
>>              --> no obvious difference
>>
>>     2.2 Guest setup: 128G RAM, 4 vCPU
>>         2.2.1 Idle guest live migration time
>>             Optimization v.s. Legacy = 5294ms vs 41651ms
>>             --> ~87% reduction
>>         2.2.2 Guest live migration with Linux compilation workload
>>           1) Live Migration Time:
>>             Optimization v.s. Legacy = 8816ms v.s. 54201ms
>>             --> 84% reduction
>>           2) Linux Compilation Time:
>>              Optimization v.s. Legacy = 8min30s v.s. 8min36s
>>              --> no obvious difference
>>
>> ChangeLog:
>> v36->v37:
>>     - free the reported pages to mm when receives a DONE cmd from host.
>>       Please see patch 1's commit log for reasons. Please see patch 1's
>>       commit for detailed explanations.
>>
>> For ChangeLogs from v22 to v36, please reference
>> https://lkml.org/lkml/2018/7/20/199
>>
>> For ChangeLogs before v21, please reference
>> https://lwn.net/Articles/743660/
>>
>> Wei Wang (3):
>>   virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT
>>   mm/page_poison: expose page_poisoning_enabled to kernel modules
>>   virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON
>>
>>  drivers/virtio/virtio_balloon.c     | 374 ++++++++++++++++++++++++++++++++----
>>  include/uapi/linux/virtio_balloon.h |   8 +
>>  mm/page_poison.c                    |   6 +
>>  3 files changed, 355 insertions(+), 33 deletions(-)
>>


  reply	other threads:[~2018-12-27 11:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27  1:32 Wei Wang
2018-08-27  1:32 ` [PATCH v37 1/3] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT Wei Wang
2018-12-27 12:03   ` Christian Borntraeger
2018-12-28  3:12     ` Wei Wang
2018-12-28  8:03       ` Christian Borntraeger
2018-08-27  1:32 ` [PATCH v37 2/3] mm/page_poison: expose page_poisoning_enabled to kernel modules Wei Wang
2018-08-27  1:32 ` [PATCH v37 3/3] virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON Wei Wang
2018-10-25  0:58 ` [PATCH v37 0/3] Virtio-balloon: support free page reporting Michael S. Tsirkin
2018-10-25 10:18   ` Wei Wang
2018-12-27 11:31 ` Christian Borntraeger
2018-12-27 11:59   ` Christian Borntraeger [this message]
2018-12-27 12:17     ` Christian Borntraeger
2018-12-28  6:41       ` Wei Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=de167161-b586-6aee-d6a5-a90d47bbe1d4@de.ibm.com \
    --to=borntraeger@de.ibm.com \
    --cc=akpm@linux-foundation.org \
    --cc=cohuck@redhat.com \
    --cc=dgilbert@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=liliang.opensource@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=mst@redhat.com \
    --cc=nilal@redhat.com \
    --cc=pasic@linux.ibm.com \
    --cc=pbonzini@redhat.com \
    --cc=peterx@redhat.com \
    --cc=quan.xu0@gmail.com \
    --cc=quintela@redhat.com \
    --cc=riel@redhat.com \
    --cc=torvalds@linux-foundation.org \
    --cc=virtio-dev@lists.oasis-open.org \
    --cc=virtualization@lists.linux-foundation.org \
    --cc=wei.w.wang@intel.com \
    --cc=yang.zhang.wz@gmail.com \
    --subject='Re: [PATCH v37 0/3] Virtio-balloon: support free page reporting' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).